Ana Pinto

research interest

Cooperation between unrelated individuals has attracted a lot of research interest for two main reasons. First, it presents a challenge for evolutionary theory: why do individuals perform a behaviour that increases the fitness of another individual? Second, it has been proposed that the ecological need to perform complex social behaviours like cooperation selects for an increase in cognitive abilities. The aim of my PhD is to integrate these two main research questions in a project on the cleaner wrasse Labroides dimidiatus. This mutualism between cleaners and their client reef fish has been studied in quite some detail, which allows me to develop quite fine-tuned hypotheses concerning cooperation and the selective pressures on the cleaners' interspecific social competence.

I have completed experiments on the first major part of my thesis, which has focused on a more detailed understanding of image scoring in a communication network and resulting audience effects. I found that cleaners flexibly adjust service quality to the relative value of current clients versus bystander. Thus, their behaviour is very much fine-tuned and not a fixed action pattern. Moreover, they are even capable of refraining completely from feeding providing tactile stimulation instead if this allows them to access a more attractive client. The results show that the behaviour and performance of the cleaner fish Labroides dimidiatus becomes more cooperative in the presence of a bystander.

The major aim of the second part of my PhD thesis is to test how important interspecific social competence is for the foraging success of cleaners. The 'Machiavellian intelligence' hypothesis proposes that the evolution of brain size and distinctive cognitive abilities have evolved via intense social behaviour including cooperation and defection. However, the knowledge about cognitive mechanisms underlying social competence remains insufficient. In recent years, several studies on cognitive abilities show that these aptitudes are not only found in primates but in other animal taxa as well. Thus, the basic assumption behind the ecological approach to the evolution of cognitive abilities is that any species should be understood according to its specific ecological challenges under natural conditions rather than by its evolutionary proximity to humans or brain size. In this context, it appears clear that the main selective force on cleaner wrasses is to maximise the food intake over their 2000 interactions per day and hence on their ability to cooperate, manipulate and exploit clients.